Table 3.

Biomaterials used in hydrogels to deliver viral vectors.

Viral vectors	Materials	Systems	Genes	Release profiles	Efficacy	Targets	References
Adenoviral	Collagen	IgG complexation in collagen gel	GFP	Controlled release	70% transduction at day 1, decreasing thereafter	Rat aortic smooth muscle cells	[92]
			GFP	Slow release	Bioactivity decreased	Fibroblasts	[93]
	Fibrin		GFP	Slow release	Half-maximal activity at 45 h	Fibroblasts, i.m. injection (mouse)	[93]
			BMP-7		Bone formation at 4 weeks
			lacZ	Sustained release for 192 h	Enhanced bioactivity	Fibroblasts	[94]
Lentiviral	Fibrin	Hydrogel complexed with hydroxyapatite nanoparticles		Initial burst of release (40% at 4 h), controlled released for 6 days (75%)	Expression reduced in the presence of HA, decline between days 9 and 35	HEK293T cells, s.c. injection (mouse)	[95]
rAAV	Fibrin	FG	GFP	Biphasic higher release at low fibrin concentration (100% released at 2 weeks)	High efficiency at low FG concentration, decline after 8 days	hMSCs	[29]
			TGF-β1
	RAD-16-I	Self-assembling peptide hydrogel pure or combined with HA	RFP	Faster release at high peptide concentration (0.4%), complete release at 6–10 days except for RAD spheres at 0.4% with 90% of release only after 21 days	80% transduction efficiency with spheres at 0.4%, time-course decline of expression	hMSCs	[37]
			lacZ
	Alginate	Alginate/poloxamer composite systems cross-linked at room temperature (AlgPH155+PF127 [C]) or high temperature (AlgPH155+PF127 [H])	lacZ	(AlgPH155+PF127 [C]) led to the most controlled release profile	Higher transduction efficiency with AlgPH155+PF127 [H]	hMSCs	[22]

rAAV: recombinant adeno-associated viral vector; RAD-16-I: self-assembling peptide with (RADA)₄ sequence; FG: fibrin glue; HA: hyaluronic acid; AlgPH: sodium alginate; PF127: poloxamer F127; GFP: green fluorescent protein; BMP: bone morphogenetic protein; lacZ: E. coliβ-galactosidase; TGF-β: transforming growth factor beta; RFP: red fluorescent protein; i.m.: intramuscular; hMSCs: human mesenchymal stem cells.